EP4146021A1 - Aerosol generating material - Google Patents

Abstract

The invention relates to aerosol generating materials for inclusion in an aerosol provision system, such as an apparatus for heating aerosol generating material to volatilise at least one component of the aerosol generating material, the aerosol generating material including a volatile component in solid particulate form, and an active substance. The invention also relates to methods for preparing such materials and apparatus comprising such materials.

Description

Aerosol generating material Technical Field

The invention relates to aerosol generating material for inclusion in an aerosol provision system, such as an apparatus for heating aerosol generating material to volatilise at least one component of the aerosol generating material, the aerosol generating material including a volatile component in solid particulate form, and an active substance. The invention also relates to methods for preparing such materials, and systems including them.

Background

Smoking articles such as cigarettes, cigars and the like burn tobacco during use to create tobacco smoke. Attempts have been made to provide alternatives to these articles by creating products that release compounds without combusting. Examples of such products are so-called “heat not burn” products or tobacco heating devices or products, which release compounds by heating, but not burning, smokeable material.

It is also known to include flavours in smoking articles to add specific desirable flavours to the aerosol generated by the smoking article. This has been achieved in a variety of different ways, including the use of crushable capsules that contain flavour compositions.

Summary

According to a first aspect of the invention, there is provided an aerosol generating material comprising at least one particle incorporating a volatile component in solid form within said composition, and at least one particle comprising an active substance, wherein the volatile component has a vapour pressure at 20°C which is greater than or equal to the vapour pressure of the active substance at 20°C, and wherein the release of the active substance from the aerosol generating material is controlled by competition with the release of the volatile component.

In some embodiments, the aerosol generating material is for inclusion in an aerosol provision system. In some embodiments, the active substance is nicotine. In some embodiments, the particles comprising the active substance are tobacco particles.

In some embodiments, the vapour pressure of the volatile component is at least 6 Pa at 20°C.

In some embodiments, the volatile component is a volatile flavour. In some embodiments, the volatile component is selected from the group consisting of menthol, limonene, linalool, camphene and eucalyptol.

In some embodiments, the volatile component does not have a distinctive or characteristic flavour.

In some embodiments, the pH of the aerosol generating material is from about 4 to about 9.5.

In some embodiments, the pH of the aerosol generating material is increased by the addition of one or more bases or a basic buffer system. In some embodiments, the one or more base is selected from the group consisting of hydroxides, carbonates and hydrogen carbonates, optionally wherein the one or more base is selected from the group consisting of: potassium hydroxide, sodium hydroxide, sodium carbonate and sodium bicarbonate. In some embodiments, the particles comprising an active substance have an average diameter no greater than 3 mm, no greater than 1 mm, no greater than 0.5 mm, or no greater than 0.3 mm.

In some embodiments, the particles incorporating a volatile component are particles that consist of the volatile component.

In some embodiments, the particles incorporating a volatile component have an average diameter no greater than 3 mm, no greater than 1 mm, no greater than 0.5 mm, or no greater than 0.3 mm. In some embodiments, the aerosol generating material further comprises one or more aerosol forming agent. In some embodiments, the aerosol forming agent is selected from the group consisting of glycerol, propylene glycol and glyceryl triacetate. In some embodiments, the aerosol generating material further comprises one or more binder. In some embodiments, the one or more binder is selected from the group consisting of: thermoreversible gelling agents, such as gelatin; starches; polysaccharides; pectins; celluloses; cellulose derivatives, such as carboxymethylcellulose; and alginates.

In some embodiments, a precursor composition comprising the volatile component particles and the particles comprising an active substance is granulated or spheronised to form the agglomerated structure. In some embodiments, a precursor composition comprising the volatile component particles and the particles comprising an active substance is extruded to form the agglomerated structure.

In some embodiments, the aerosol generating material is in the form of granules.

According to a second aspect of the invention, there is provided an aerosol provision system comprising an aerosol generating material according to the first aspect.

In some embodiments, the system is an aerosol generating material heating system comprising an aerosol generating material which is to be heated to volatilise constituents, and optionally including a filter or filter element.

In some embodiments, the system is a hybrid system comprising an aerosol generating material which is to be heated to volatilise constituents, and a liquid which is to be heated to form a vapour, and optionally including a filter or filter element.

In some embodiments, the aerosol generating material is heated by the vapour.

In some embodiments, the liquid is a nicotine-free liquid. In some embodiments, the device includes a means for heating the liquid to form a vapour, but does not include a separate means for heating the aerosol generating material. According to a third aspect of the invention, there is provided a method for preparing an aerosol generating material comprising a volatile component for use in an aerosol provision system, the method comprising incorporating the volatile component into the composition in solid form, wherein the volatile component has a vapour pressure at 20°C which is greater than or equal to the vapour pressure of the active substance at 20°C.

In some embodiments, the aerosol generating material is formed from a precursor composition comprising particles comprising the volatile component and particles comprising an active substance.

In some embodiments, the precursor composition is granulated or spheronised to form the agglomerated structure.

In some embodiments, the precursor composition is extruded to form the agglomerated structure.

According to a fourth aspect of the invention, there is provided an apparatus for heating aerosol generating material to volatilise at least one component of the aerosol generating material, and a nicotine-free liquid which is to be heated to form a vapour, wherein the aerosol generating material comprises an aerosol generating material according to the first aspect, and wherein the aerosol generating material is heated by the vapour.

In some embodiments, the apparatus includes a means for heating the liquid to form a vapour, but not including a separate means for heating the aerosol generating material.

In some embodiments, the pH is increased by the addition of one or more bases or a basic buffer system. According to a fifth aspect of the invention, there is provided a particle incorporating a volatile component in solid form, wherein the volatile component has a vapour pressure at 20°C which is greater than or equal to the vapour pressure of the active substance at 20°C, for use in controlling the release of nicotine in an aerosol generating material. Brief Description of the Drawings

Embodiments of the invention will now be described, by way of example only, with reference to accompanying drawings, in which:

Figure 1 is a flow chart showing key steps of a process according to embodiments of the present invention; Figure 2 is a schematic representation of some extruded granules;

Figure 3 is a schematic cross-sectional view of a tobacco heating product for heating aerosol generating material to volatilise at least one component of the aerosol generating material;

Figure 4 is a schematic view of a hybrid system for heating aerosol generating material to volatilise at least one component of the aerosol generating material; and

Figure 5 is a schematic cross-sectional view of an example of a cartridge containing multiple particles of an aerosol generating material.

Detailed Description The invention relates to aerosol generating material comprising a volatile component in solid particulate form, and nicotine. The aerosol generating material is able to release the volatile component and active substance when heated.

In some embodiments, the aerosol generating material is in particulate or monolithic form. In some embodiments, the aerosol generating material is an agglomerated structure. This means that they are a mass or cluster formed by fusing or adhering multiple particles to one another.

The aerosol generating material is able to provide a consistent and extended release of the active substance from the aerosol generating material as a result of the presence in the aerosol generating material of a volatile component that has a vapour pressure at 20°C that is greater than or equal to the vapour pressure of the active substance at 20°C. Whilst not wishing to be bound by any particular theory, it is believed that the active substance and volatile component compete to volatise from the aerosol generating material. The presence of the volatile component, which is readily volatilised upon heating is thought to supress the volatilisation of the active substance, slowing its release from the aerosol generating material. This is particularly advantageous in tobacco heating devices and hybrid devices where the nicotine is generally seen to be rapidly volatilised, providing an initial rapid release of nicotine which is then followed by a sharp drop off in nicotine release, leading to an inconsistent nicotine delivery and user experience.

Therefore, in some embodiments of the invention, the presence of the volatile component controls the release of the active substance from the aerosol generating material. This is an unexpected and highly beneficial effect of the materials described herein.

Volatile component particles

In some embodiments, the aerosol generating material comprises a particle or particles incorporating a volatile component.

In some embodiments, these volatile component particles consist essentially of a particle of the volatile component in solid form. For example, the particles may comprise particles of menthol, or other volatile component that can be solid at room temperature. In other embodiments, the particles may comprise a carrier material and the volatile component deposited, in solid form, on or in the carrier material.

In some embodiments, the volatile component comprises, consists essentially or, or consists of menthol. For example, the aerosol generating material may comprise particles of menthol.

In some embodiments, the particles of solid volatile component are distributed within the aerosol generating material. In some embodiments, these particles are generally homogenously distributed within the material. In other embodiments, the distribution of the particles of volatile component is not homogenous and is designed to provide release of the volatile component at a predetermined point during the heating of the aerosol generating material.

In some embodiments, the particles of volatile component have an average particle size of about 0.1 to about 3 mm, as determined by sieving. In some embodiments, the use of smaller particles of the volatile component may be preferred, for example, with an average particle size of from about o.i to about 1 mm, or from about 0.5 mm to about 2 mm, as determined by sieving.

Active substance The active substance as used herein may be a physiologically active material, which is a material intended to achieve or enhance a physiological response. The active substance may for example be selected from nutraceuticals, nootropics, psychoactives. The active substance may be naturally occurring or synthetically obtained. The active substance may comprise for example nicotine, caffeine, taurine, theine, vitamins such as B6 or B12 or C, melatonin, cannabinoids, or constituents, derivatives, or combinations thereof. The active substance may comprise one or more constituents, derivatives or extracts of tobacco, cannabis or another botanical. In some embodiments, the active substance comprises nicotine. In some embodiments, the active substance comprises caffeine, melatonin or vitamin B12.

As noted herein, the active substance may comprise or be derived from one or more botanicals or constituents, derivatives or extracts thereof. As used herein, the term "botanical" includes any material derived from plants including, but not limited to, extracts, leaves, bark, fibres, stems, roots, seeds, flowers, fruits, pollen, husk, shells or the like. Alternatively, the material may comprise an active compound naturally existing in a botanical, obtained synthetically. The material maybe in the form of liquid, gas, solid, powder, dust, crushed particles, granules, pellets, shreds, strips, sheets, or the like. Example botanicals are tobacco, eucalyptus, star anise, hemp, cocoa, cannabis, fennel, lemongrass, peppermint, spearmint, rooibos, chamomile, flax, ginger, ginkgo biloba, hazel, hibiscus, laurel, licorice (liquorice), matcha, mate, orange skin, papaya, rose, sage, tea such as green tea or black tea, thyme, clove, cinnamon, coffee, aniseed (anise), basil, bay leaves, cardamom, coriander, cumin, nutmeg, oregano, paprika, rosemary, saffron, lavender, lemon peel, mint, juniper, elderflower, vanilla, wintergreen, beefsteak plant, curcuma, turmeric, sandalwood, cilantro, bergamot, orange blossom, myrtle, cassis, valerian, pimento, mace, damien, marjoram, olive, lemon balm, lemon basil, chive, carvi, verbena, tarragon, geranium, mulberry, ginseng, theanine, theacrine, maca, ashwagandha, damiana, guarana, chlorophyll, baobab or any combination thereof. The mint maybe chosen from the following mint varieties: Mentha Arventis, Mentha c.v., Mentha niliaca, Mentha piperita, Mentha piperita citrata c.v., Mentha piperita c.v, Mentha spicata crispa, Mentha cardifolia, Mentha longifolia, Mentha suaveolens variegata, Mentha pulegium, Mentha spicata c.v. and Mentha suaveolens

In some embodiments, the active substance comprises or is derived from one or more botanicals or constituents, derivatives or extracts thereof and the botanical is tobacco. In some embodiments, the active substance comprises or is derived from one or more botanicals or constituents, derivatives or extracts thereof and the botanical is selected from eucalyptus, star anise, cocoa and hemp.

In some embodiments, the active substance comprises or is derived from one or more botanicals or constituents, derivatives or extracts thereof and the botanical is selected from rooibos and fennel.

Particles of active substance

In some embodiments, the aerosol generating material comprises a particle or particles comprising one or more active substances. Herein, particles of an active substance are also referred to as “active particles”.

In some embodiments, the active substance is a plant derived active substance. In such embodiments, the particles of active substance maybe plant particles comprising the active substance. Alternatively, the particles of active substance may comprise the active substance deposited in or on particles of carrier material.

In some embodiments, the active substance is nicotine. The nicotine particles may be particles of tobacco material. Alternatively, the nicotine particles may comprise a carrier material and nicotine.

In some embodiments, the particles comprising the active substance present in the aerosol generating material have a size small enough to ensure that multiple such particles can be agglomerated to form an aerosol provision system having desired dimensions based upon their intended use. Smaller particles of active substance have a greater surface area to volume ratio and they may therefore exhibit enhanced release of the active substance compared to particles of larger sizes. In addition, the size of the active particles (and of other particles in the precursor composition) will have an effect on the porosity and density of the agglomerated structures and the particulate aerosol generating material. Thus, the size of the active particles may be selected to produce a more porous agglomerated structure, which will have an impact on the release of the active substance. Thus, the size of the active particles is another factor that may be adjusted in order to influence the release of the active substance, in particular where the particulate aerosol generating material has an agglomerated structure made by granulation as opposed to extrusion.

The preferred size of the active particles may also depend upon the method used to form the agglomerated structures. For example, extrusion processes can be sensitive to the size of the particles within the composition being extruded. Specifically, in some embodiments where the precursor composition is extruded to form the agglomerated structure, it maybe desirable for the particles in the precursor composition, including the active particles, to have an average particle size of no greater than about 3 mm, of no greater than 1 mm, of no greater than about 0.5 mm, or to have an average particle size of no greater than about 0.3 mm, when measured by sieving.

In some embodiments, it may be desirable for the active particles in the precursor composition and/or in the aerosol generating material to have an average particle size of no greater than about 3 mm, of no greater than 1 mm, of no greater than about 0.5 mm, or to have an average particle size of no greater than about 0.3 mm, when measured by sieving. In some embodiments, the average particle size is within the range of about 0.1 to about 3 mm, of about 0.1 to about 1 mm, of about 0.1 to about 0.5 mm, of about 0.1 to about 0.4 mm, or in the range of about 0.2 to about 0.3 mm. In some embodiments, at least about 90% of the particles of the precursor composition will have a particle size within the range of about 0.1 to about 3 mm, or of about 0.1 to about 1 m, or of about 0.1 to about 0.5 mm. In some embodiments, at least about 90% of the active particles of the precursor composition will have a particle size within the range of about 0.1 to about 3 mm, or of about 0.1 to about 1 mm, or of about 0.1 to 0.5 mm. In some embodiments, none of the particles in the precursor composition have a particle size greater than 5 mm, greater than 4 mm, greater than 2 mm, greater than 1.5 mm, or greater than about 1 mm.

In some embodiments, the active particles are particles of plant material. Where the active substance is or includes nicotine, the active particles may be particles of tobacco material (referred to herein as tobacco particles).

Particles of the desired size may be formed by grinding, shredding, cutting or crushing plant material such as tobacco material. Suitable machinery to create such plant particles includes, for example, shredders, cutters, or mills, such as hammer mills, roller mills or other types of commercially available milling machinery. The size of the plant particles is selected to provide particles which can be readily prepared from a variety of different types of plant material, which can be formed into agglomerated structures using the processes described herein and having the properties described herein, and which provide a source of active substances that are readily released.

Without wishing to be bound by any one particular theory, it is speculated that the chopping of the tobacco to form the tobacco particles enhances the release of tobacco constituents including volatile flavours and aromatic constituents, as well as nicotine. The increased surface area of the tobacco particles is also thought to aid volatilisation. The smaller tobacco particles also improve the homogeneity of agglomerated structures formed therefrom together with other components.

The tobacco material used to form the tobacco particles may be any type of tobacco and any part of the tobacco plant, including tobacco lamina, stem, stalk, ribs, scraps and shorts or mixtures of two or more thereof. Suitable tobacco materials include the following types: Virginia or flue-cured tobacco, Burley tobacco, Oriental tobacco, or blends of tobacco materials, optionally including those listed here. The tobacco may be expanded, such as dry-ice expanded tobacco (DIET), or processed by any other means. In some embodiments, the tobacco material may be reconstituted tobacco material.

The tobacco maybe pre-processed or unprocessed, and maybe, for instance, solid stems (SS); shredded dried stems (SDS); steam treated stems (STS); or any combination thereof. The tobacco material may be fermented, cured, uncured, toasted, or otherwise pre-treated. pH Adjustment In some embodiments, the aerosol generating material is formed from a precursor composition comprising the active particles, wherein the pH of the active particles has been adjusted to a basic pH. For example, the pH maybe adjusted to at least about 7.5. The pH may be adjusted by the addition of one or more bases. Alternatively, the pH may be adjusted by the use of a buffer solution.

In some embodiments, the aerosol generating material comprises active particles and one or more bases or a basic buffer system, so that the active particles have a basic pH. For example, the pH maybe at least about 7.5.

The purpose of adjusting the pH of the active particles and/or of the precursor composition is to provide the active substance in a chemical form that is readily released from the aerosol generating material, and/or they are readily transferred to the aerosol generated by the smoking article.

In some embodiments, the pH of the active particles is adjusted to at least about 7.5, at least about 8, at least about 8.5, at least about 9, at least about 9.5 or at least about 10. In some embodiments, the pH is adjusted to no higher than about 14, no higher than about 13.5, no higher than about 13, no higher than about 12.5, no higher than about 12, no higher than about 11.5, no higher than about 11, no higher than about 10.5 or no higher than about 10. In some embodiments, the pH of the active particles is adjusted to from about 8 to about 10, or from about 8.5 to about 9.5.

In some embodiments, the pH of the aerosol generating material is at least about 7.5, at least about 8, at least about 8.5, at least about 9, at least about 9.5 or at least about 10. In some embodiments, the pH is no higher than about 14, no higher than about 13.5, no higher than about 13, no higher than about 12.5, no higher than about 12, no higher than about 11.5, no higher than about 11, no higher than about 10.5 or no higher than about 10. In some embodiments, the pH of the aerosol generating material is adjusted to from about 8 to about 10, or from about 8.5 to about 9.5.

In some embodiments, the pH of the aerosol generating material is adjusted to from about 7.5 to about 10, or from about 8 to about 9, or to about 8.5, about 9, about 9.5 or about 10. In some embodiments, the base used to adjust the pH is a hydroxide or a carbonate. Hydroxides used may be monoacidic bases, diacidic bases or triacidic bases. Suitable bases include, for example, potassium hydroxide, calcium hydroxide, silver hydroxide, ammonium hydroxide, magnesium hydroxide, sodium carbonate, sodium bicarbonate (also known as sodium hydrogen carbonate), and potassium carbonate.

The base may be added in the form of a liquid, such as an aqueous or non-aqueous solution or suspension, or in the form of a solid, such as a powder. In some embodiments, the pH of the particles comprising a volatile component is not adjusted.

In some embodiments, the aerosol generating material is formed from a precursor composition comprising a mixture of particles incorporating a volatile component and particles comprising an active substance. In some embodiments, the precursor composition further comprises a pH adjuster. In embodiments where the volatile component particles, active particles and pH adjuster are dry, for example where the base is in the form of a dry powder, the pH of the precursor composition will be adjusted (compared to the pH of the particles without the pH adjuster) once water is added to the composition.

As used herein, the pH of the precursor composition or of the aerosol generating material refers to the pH once water is added to the composition or material where the composition or material is dry.

In some embodiments, the buffer system used to adjust the pH is a mixture of a weak base and its conjugate acid. Suitable buffer systems include, for example, ones having a pH of at least about 7.5, at least about 8, at least about 8.5 or at least about 9. In some embodiments, the pH of the buffer system is from about 8 to about 10, or from about 8.5 to about 9.5. Suitable buffer systems include, for example, those based on ammonia, carbonates or hydroxides, with suitable counterions. An example of a specific buffer system is a mixture of ammonia and ammonium chloride.

Additional components of the aerosol generating material In some embodiments, the aerosol generating material having an agglomerated structure is formed from a precursor composition comprising active particles and volatile component particles. In some embodiments, the precursor composition and/ or the aerosol generating material does not include a binder or binding additive. In other embodiments, the precursor composition comprises a binder or binding additive. The binding additive may be selected to assist in the formation of an agglomerated structure by helping to adhere the particles to each other and to other components in the aerosol generating material. Suitable binding additives include, for example, thermoreversible gelling agents such as gelatin, starches, polysaccharides, pectins, alginates, wood pulp, celluloses, and cellulose derivatives such as carboxymethylcellulose.

In some embodiments, the precursor composition and/or the aerosol generating material further comprises a diluent. The diluent may be in solid or liquid form. In some embodiments, the diluent is inert or substantially inert.

In some embodiments, the agglomerated structure formed from the precursor composition may have an increased surface area by including in the precursor composition particles of an inert filler material. Suitable inert fillers may be porous or non-porous.

In some embodiments, the precursor composition and/or the aerosol generating material further comprises at least one aerosol forming agent which may be, for instance, a polyol aerosol generator or a non-polyol aerosol generator, preferably a non polyol aerosol generator. It may be a solid or liquid at room temperature, but preferably is a liquid at room temperature. Suitable polyols include sorbitol, glycerol, and glycols like propylene glycol or triethylene glycol. Suitable non-polyols include monohydric alcohols, high boiling point hydrocarbons, acids such as lactic acid, and esters such as diacetin, triacetin, triethyl citrate or isopropyl myristate. A combination of aerosol forming agents may be used, in equal or differing proportions. Glycerol and propylene glycol may be particularly preferred.

In some embodiments, the precursor composition and/or aerosol generating material may include a flavour- modifier, to modify the flavour provided by the tobacco particles or to add flavour. In some embodiments, the flavour-modifier may be included in the precursor composition. Alternatively or in addition, the flavour-modifier may be added to or applied to the agglomerated structure. As used herein, the terms "flavour" and "flavourant" refer to materials which, where local regulations permit, maybe used to create a desired taste, aroma or other somatosensorial sensation in a product for adult consumers. They may include naturally occurring flavour materials, botanicals, extracts of botanicals, synthetically obtained materials, or combinations thereof (e.g., tobacco, cannabis, licorice (liquorice), hydrangea, eugenol, Japanese white bark magnolia leaf, chamomile, fenugreek, clove, maple, matcha, menthol, Japanese mint, aniseed (anise), cinnamon, turmeric, Indian spices, Asian spices, herb, wintergreen, cherry, berry, red berry, cranberry, peach, apple, orange, mango, clementine, lemon, lime, tropical fruit, papaya, rhubarb, grape, durian, dragon fruit, cucumber, blueberry, mulberry, citrus fruits, Drambuie, bourbon, scotch, whiskey, gin, tequila, rum, spearmint, peppermint, lavender, aloe vera, cardamom, celery, cascarilla, nutmeg, sandalwood, bergamot, geranium, khat, naswar, betel, shisha, pine, honey essence, rose oil, vanilla, lemon oil, orange oil, orange blossom, cherry blossom, cassia, caraway, cognac, jasmine, ylang-ylang, sage, fennel, wasabi, piment, ginger, coriander, coffee, hemp, a mint oil from any species of the genus Mentha, eucalyptus, star anise, cocoa, lemongrass, rooibos, flax, ginkgo biloba, hazel, hibiscus, laurel, mate, orange skin, rose, tea such as green tea or black tea, thyme, juniper, elderflower, basil, bay leaves, cumin, oregano, paprika, rosemary, saffron, lemon peel, mint, beefsteak plant, curcuma, cilantro, myrtle, cassis, valerian, pimento, mace, damien, marjoram, olive, lemon balm, lemon basil, chive, carvi, verbena, tarragon, limonene, thymol, camphene), flavour enhancers, bitterness receptor site blockers, sensorial receptor site activators or stimulators, sugars and/or sugar substitutes (e.g., sucralose, acesulfame potassium, aspartame, saccharine, cyclamates, lactose, sucrose, glucose, fructose, sorbitol, or mannitol), and other additives such as charcoal, chlorophyll, minerals, botanicals, or breath freshening agents. They may be imitation, synthetic or natural ingredients or blends thereof. They may be in any suitable form, for example, liquid such as an oil, solid such as a powder, or gas.

In some embodiments, the flavour comprises menthol, spearmint and/ or peppermint. In some embodiments, the flavour comprises flavour components of cucumber, blueberry, citrus fruits and/or redberry. In some embodiments, the flavour comprises eugenol. In some embodiments, the flavour comprises flavour components extracted from tobacco. In some embodiments, the flavour comprises flavour components extracted from cannabis.

In some embodiments, the flavour may comprise a sensate, which is intended to achieve a somatosensorial sensation which are usually chemically induced and perceived by the stimulation of the fifth cranial nerve (trigeminal nerve), in addition to or in place of aroma or taste nerves, and these may include agents providing heating, cooling, tingling, numbing effect. A suitable heat effect agent may be, but is not limited to, vanillyl ethyl ether and a suitable cooling agent may be, but not limited to eucolyptol, WS-3.

In some embodiments, the precursor composition and/or the aerosol generating material further comprises a preservative. Suitable preservatives would be readily known to the skilled person and would include, for example, those that are safe for use in products producing inhalable aerosols. Examples of preservatives that might be used include: propylene glycol, carvacrol, thymol, L-menthol, 1,8-cineole, phenoxyethanol, PhytoCide, sorbic acid and its salts, sodium hydroxymethylglycinate, ethylhexylglycerin, parabens and vitamins such as vitamin E or vitamin C. In some embodiments, neither the precursor composition nor the aerosol generating material includes a gelling agent.

Form of agglomerated structures

In some embodiments, the aerosol generating material is in particulate form, being small, separate particles. In most embodiments, multiple particles will be incorporated into an apparatus in order to have the desired effect on the aerosol of the apparatus.

In some embodiments, the particulate aerosol generating material has an average size (as measured by sieving) of from about 0.5 mm to about 4 mm. In some embodiments, it may be preferable for the granules to have an average size of from about 0.7 mm to about 3 mm.

In other embodiments, the aerosol generating material is in monolithic form, being larger articles. In most embodiments, a single monolithic component will be incorporated into an apparatus in order to have the desired effect on the aerosol of the apparatus. In some embodiments, the monolithic components are roughly spherical or cylindrical in shape. They may have a diameter of from about 4 mm to about 10 mm. In some embodiments, the diameter may be from about 5 mm to about 8 mm. Cylindrical components may additionally have a length of from about 5 mm to about 80 mm, from about 15 mm to about 50 mm, or from about 20 mm to about 30 mm.

Forming the agglomerated structures

Figure 1 is a flow chart showing the key steps in the processes of some embodiments of the present invention. A tobacco starting material, which may be pre-treated or pre- processed, is ground to the desired particle size. The pH is adjusted, either by adding one or more bases or by adding a buffer solution to the tobacco particles. Particles of volatile component are added to the tobacco particles to form the precursor material. Any additional components may be added to the precursor material. These additional components may be in liquid form or is solid form. Additional solid components are preferably in particulate or powder form. The additional components may be added before, during or after the pH adjustment step. An agglomerated structure is then formed from the resultant precursor composition, by adhering the pH-adjusted tobacco particles and optional other components to form multi-particle entities.

In some embodiments, water may be added to the precursor composition as a processing aid. For example, the presence of water may help to dissolve components of the precursor composition, such as the pH adjusting agent and sugars, and/or it may assist with binding or improve agglomeration.

In some embodiments, the agglomerated structure maybe formed from the precursor composition by a process including one or more steps selected from the group consisting of granulation, extrusion and spheronisation. Granulation

Granulation of the precursor composition involves the binding or fusing together of the particles of the precursor composition to form larger, multi-particle entities which are referred to herein as agglomerated structures. The multi-particle entities formed by granulation are called granules and they may have various geometric shapes, including, for example, the general form of spheres, cylinders, and the like. In one embodiment, the granulation step used is wet granulation. In wet granulation, granules are formed by the addition of a granulation liquid onto a powder bed. Agitation in the system, along with the wetting of the components within the precursor composition, results in the aggregation of the particles to produce wet granules. The granulation liquid may be at least partially removed by drying to provide dry granules. The granulation liquid may be water-based or solvent-based. Suitable granulation liquids include, for example, water, glycerol, ethanol and isopropanol, either alone or in combination. In some embodiments, the granulation liquid comprises an aerosol forming agent, such as glycerol or one of the other agents mentioned herein, and/ or a binder or binding agent. In some embodiments, no water is added to the precursor composition to aid granulation.

In another embodiment, the granulation step used is dry granulation. In dry granulation, granules are formed without using a granulation liquid. This type of process has the advantage that it does not expose the precursor composition to moisture and so there is no requirement to expose the granules to heat in order to dry them. Forming granules by dry granulation involves compacting and densifying the precursor composition, usually under high pressure. Extrusion

Extrusion of the precursor composition involves the feeding of the precursor composition through an orifice to produce an extruded agglomerate. The process, which applies pressure to the precursor composition combined with shear forces, results in agglomerated structures.

Extrusion may be performed using one of the main classes of extruders: screw, sieve and basket, roll, ram and pin barrel extruders. A single screw or twin screw extruder maybe used. Forming the aerosol generating material by extrusion has the advantage that this processing combines mixing, conditioning, homogenizing and moulding of the precursor composition.

In some embodiments, during extrusion the free-flowing precursor composition is exposed to elevated pressure and temperature and is forced though an orifice, such as a shaping nozzle or die, to form an extruded agglomerate. In some embodiments, the extruded agglomerate has a rod-like form and/ or it may be cut into segments of a desired length as it exits the orifice. A rod-like extruded agglomerate may subsequently be cut into segments of desired length.

In some embodiments, the precursor composition is exposed to temperatures from about 40°C to about 150°C, or from about 8o°C to about 130°C, or from about 6o°C to about 95°C within the extruder. In some embodiments, including those using double extrusion, the precursor composition is exposed to temperatures from about 70°C to about 95°C within the extruder. In some embodiments, including those using single extrusion, the precursor composition is exposed to temperatures from about 6o°C to about 8o°C within the extruder. The composition may be exposed to pressures

(immediately before the die or nozzle) ranging from about 2 bar to about too bar, or from about 5 bar to about 60 bar, depending on the design of the die or nozzle being used. In some embodiments, where the active particles are particles of plant material, such as tobacco, due to the relatively high density of the extruded agglomerate and the relatively open surface of the plant particles within it, the aerosol generating material formed from the extruded agglomerate exhibits good heat transfer and mass transfer, which has a positive impact on the release of the active substance and the volatile component.

In some embodiments, the extrusion may be a generally dry process, with the precursor composition being a dry or substantially dry material that includes active particles, volatile component particles, as well as optionally other particulate materials including, for example, base, diluent, solid aerosol forming agents, solid flavour modifiers, etc.

In some embodiments, liquids maybe added to the precursor composition during the extrusion process. For example, water may be added to the precursor composition, for example as a processing aid to assist dissolution or solubilisation of components of the composition, or to aid binding or agglomeration. Alternatively or additionally, a wetting agent may be added to the precursor composition.

In some embodiments, the liquid may be an aerosol forming agent such as glycerol or others discussed herein. When liquid is added to the precursor composition in this manner, the liquid is applied not only on the surface, but, as a result of the extruder pressure combined with the intensive mixing by high shear forces, the extruded agglomerate becomes impregnated with the liquid. Where the liquid is an aerosol forming agent, this can result in a high availability of the aerosol forming agent in the agglomerated product to enhance evaporation and release of the active substance and other volatile components from the agglomerated structure.

In some embodiments, in view of the impregnation of the extruded agglomerate with the aerosol forming agent, greater volumes of this additive can be incorporated into the aerosol generating material than if the aerosol forming agent were simply being applied to the surface of the precursor composition or of the extruded agglomerate. In some embodiments, the amount of aerosol forming agent incorporated into the aerosol generating material may be at least about 1% by weight, at least about 1.5% by weight, at least about 2% by weight, at least about 3% by weight, at least about 5%, at least about 10%, at least about 15% or at least about 20% by weight. In some embodiments, the amount of aerosol forming agent incorporated into the aerosol generating material may be up to about 30% by weight and even up to about 40% by weight. High amounts of aerosol forming agent, such as at least about 10% or at least about 20% by weight, may be advantageous where the aerosol generating material is to generate an aerosol in addition to releasing the active substance and volatile components. Smaller amounts of aerosol forming agent, such as up to about 5% by weight, maybe sufficient where the aerosol generating material’s primary function is to releasing the active substance and volatile components carried by the material into an existing aerosol or air flow.

The extruded agglomerate will be shaped by the nozzle or die through which it is forced. In some embodiments, the extruded agglomerate is cut into pieces of desired length. The pieces formed in this way may be used as the aerosol generating material or they may undergo further processing.

In some embodiments, the nozzle or die is shaped to provide a solid strand of extruded agglomerate. For example, the extruded agglomerate may have the form of a solid cylindrical rod. Alternatively, the extruded agglomerate may have different cross- sectional shapes, including oval, polygonal (such as triangular, square, etc.), and stars.

In some embodiments, the extruded composition is formed into a desired shape selected to enhance or promote the release of the active substance and volatile components, for example by providing a form having a large surface area per unit volume. This large surface area maybe provided on the outer surface of the extruded agglomerate, for example by selecting cross-sectional shapes with large perimeter. Alternatively or in addition, the large surface area may be provided through the creation of channels within the extruded agglomerate. In some embodiments, the nozzle is shaped to provide an extruded agglomerate with inner channels. These inner channels provide further surface area and can enhance constituent release.

Aerosol generating material formed from such shaped extruded agglomerate sections has an inner channel structure which have advantageous adjustable strand ventilation properties and a significantly enlarged inner surface leading to improved heat and mass transfer. As a result, such shaped materials exhibit better, more uniform release of the active substance and volatile components by evaporation. Furthermore, the structure with inner channels exhibits significantly improved strength in both the radial and axial directions, which is beneficial for the further processing of the extruded agglomerate, for example when it is cut into segments.

By means of various nozzle or die designs and/or different process parameters within the extruder, including the temperature, pressure and shear forces, extruded agglomerates with different physical properties may be prepared, including different heat transfer properties, draft resistance, and capable of producing different aerosols and/ or of modifying aerosols being drawn through the extruded agglomerate.

In some embodiments, the extruded agglomerate is shaped upon discharge from the extruder. In some embodiments, the extruded agglomerate is cut to an initial length, for example l metre, and allowed to cool before then being cut into sections of the desired length to provide the aerosol generating material in the form of particles of the desired dimensions. In some embodiments, the extruded agglomerate maybe cooled just before or just as it leaves the extruder. In some embodiments, the cooling is intensive and involves exposing the extruded agglomerate, which will be at an elevated temperature, for example from about 30°C to about ioo°C, or from about 40°C to about 70°C, to a cooling means that will reduce the temperature to within a range of from about o°C to about 70°C, from about o°C to about 50°C, from about 5°C to about 25°C or from about 5°C to about 15°C. This rapid cooling of the extruded agglomerate may enhance the internal and external stability of the extruded agglomerate. In some embodiments, it is the nozzle or die that is cooled to achieve this effect.

In some embodiments, it may be desirable to control the temperature of the precursor composition during extrusion, including before feeding the composition through the nozzle or die. This is especially the case where the precursor composition includes temperature sensitive components, such as aerosol forming agents such as glycerol. Thus, in some embodiments, extrusion of the precursor composition includes reducing the temperature of the precursor composition before it reaches the nozzle or die. Such cooling of the precursor composition may result in the formation of an extruded agglomerate with beneficial properties, or may improve the strand-shaping process, for example where channels are to be formed within the extruded agglomerate strand.

In some embodiments, spheronisation is used to further process extruded segments. These segments are typically cylindrically-shaped and are cut or broken into uniform lengths following extrusion. They are then gradually transformed into spherical shapes by spheronisation. This shaping occurs as a result of plastic deformation and spheronisation can lead to spherical agglomerated structures, often with a nearly uniform diameter.

Incorporation into an apparatus

One or more particles of the aerosol generating material may be incorporated into an aerosol provision system, such as an apparatus for heating aerosol generating material to volatilise at least one component of the aerosol generating material. The aerosol generating material included in the aerosol provision system may comprise, consist essentially of, or consist of an aerosol generating material as described herein. In some embodiments, the aerosol generating material used in the aerosol provision system further comprises one or more other aerosol generating materials, such as tobacco material.

As used herein, an aerosol provision system includes non-combustible aerosol provision systems that release compounds from an aerosol generating material without combusting the aerosol-generating material, such as tobacco heating products, and hybrid systems to generate aerosol using a combination of aerosol-generating materials. According to the present disclosure, a “non-combustible” aerosol provision system is one where a constituent aerosol-generating material of the aerosol provision system (or component thereof) is not combusted or burned in order to facilitate delivery of at least one substance to a user.

In some embodiments, the delivery system is a non-combustible aerosol provision system, such as a powered non-combustible aerosol provision system.

In some embodiments, the non-combustible aerosol provision system is an electronic cigarette, also known as a vaping device or electronic nicotine delivery system (END), although it is noted that the presence of nicotine in the aerosol generating material is not a requirement.

In some embodiments, the non-combustible aerosol provision system is an aerosol-generating material heating system, also known as a heat-not-burn system.

An example of such a system is a tobacco heating system.

In some embodiments, the non-combustible aerosol provision system is a hybrid system to generate aerosol using a combination of aerosol-generating materials, one or a plurality of which may be heated. Each of the aerosol-generating materials may be, for example, in the form of a solid, liquid or gel and may or may not contain nicotine. In some embodiments, the hybrid system comprises a liquid or gel aerosol-generating material and a solid aerosol-generating material. The solid aerosol-generating material may comprise, for example, tobacco or a non- tobacco product.

Typically, the non-combustible aerosol provision system may comprise a non combustible aerosol provision device and a consumable for use with the non combustible aerosol provision device.

In some embodiments, the disclosure relates to consumables comprising aerosol generating material and configured to be used with non-combustible aerosol provision devices. These consumables are sometimes referred to as articles throughout the disclosure. In some embodiments, the non-combustible aerosol provision system, such as a non-combustible aerosol provision device thereof, may comprise a power source and a controller. The power source may, for example, be an electric power source or an exothermic power source. In some embodiments, the exothermic power source comprises a carbon substrate which may be energised so as to distribute power in the form of heat to an aerosol-generating material or to a heat transfer material in proximity to the exothermic power source.

In some embodiments, the non-combustible aerosol provision system may comprise an area for receiving the consumable, an aerosol generator, an aerosol generation area, a housing, a mouthpiece, a filter and/ or an aerosol-modifying agent.

In some embodiments, the consumable for use with the non-combustible aerosol provision device may comprise aerosol-generating material, an aerosol-generating material storage area, an aerosol-generating material transfer component, an aerosol generator, an aerosol generation area, a housing, a wrapper, a filter, a mouthpiece, and/ or an aerosol-modifying agent. The aerosol generating material may be positioned within the apparatus or device so that the nicotine and volatile components that are released become entrained in an aerosol generated by the apparatus or device upon use, modifying the properties of the aerosol. Additionally or alternatively, the aerosol generating material may itself generate an aerosol during use, said aerosol including the released nicotine and volatile components.

According to some embodiments, one or more particles of aerosol generating material are included in an aerosol provision system to volatilise components of the aerosol generating material by heating but not combusting the material (i.e., a tobacco heating product or so-called Heat-not-Burn product). In some of these products, the aerosol generating material is heated to generate an aerosol.

In some embodiments, one or more particles of aerosol generating material are to be heated by such products. In some embodiments, one or more particles of aerosol generating material may be incorporated into tobacco material to form the material to be heated. For example, the one or more particles of aerosol generating material may be dispersed within the tobacco material, such as cut tobacco or reconstituted tobacco, to contribute to the nicotine and flavour imparted by the tobacco. In other embodiments, the tobacco included in the material to be heated by the tobacco heating system consists or consists essentially of one or more particles of aerosol generating material. The aerosol generating material may be heated directly. Where the aerosol generating material is multiple particles of aerosol generating material, these may be held in a container or cartridge. At least portions of the container or cartridge may be permeable to air, to allow air to flow over or through the particles of aerosol generating material.

Figure 3 shows a cross-sectional view of an example of a tobacco heating product for heating an aerosol generating material. The apparatus 11 has a heating chamber 14 which in use contains the aerosol generating material to be heated and volatilised. In this embodiment, the aerosol generating material is in the form of a monolithic aerosol generating material 13. The aerosol generating material could however be multiple particles of aerosol generating material held in the heating chamber or provided in a cartridge like the one illustrated in Figure 5.

The apparatus 11 of Figure 3 further has an electronics/power chamber 16 which may, for example, contain electrical control circuitry and/ or a power source (not shown).

The electrical control circuitry may include a controller, such as a microprocessor arrangement, configured and arranged to control the heating of the aerosol generating material via a heating element (not shown). The electrical control circuitry may in use receive a signal from for example a puff-actuated sensor which is sensitive to for example changes in pressure or changes in rate of air flow that occur upon initiation of a draw on the apparatus 11 by a user. The electrical control circuitry can then operate so as to cause heating of the aerosol generating material “on demand”. Various arrangements for a puff-actuated sensor are available, including for example a thermistor, an electro-mechanical device, a mechanical device, an optical device, an opto-mechanical device and a micro electro mechanical systems (MEMS) based sensor. As an alternative, the apparatus may have a manually operable switch for a user to initiate a puff.

The heating chamber 14 is contained within the housing 12. There may be a support and/ or insulating means (not shown) positioned between the heating chamber 14 and the housing 12, for example to assist in heat-insulating the housing 12 from the heating chamber 14, so that the housing 12 does not become hot or at least too hot to touch during use.

The housing 12 includes an inlet 15 through which air is drawn into the apparatus. The housing 12 also includes an outlet 17 at a mouthpiece 18 of the apparatus 11. Air is drawn into the apparatus 11 through the inlet 15, travels through the apparatus picking up the active substance and other volatile constituents released by the aerosol generating material 13, and the resulting aerosol generated by the apparatus 11 leaves the apparatus 11 through the outlet 19 and is inhaled by the user.

According to some embodiments, one or more particles of the aerosol generating material are included in a so-called hybrid system for heating aerosol generating material to volatilise at least one component of an aerosol generating material. In some of these products, the aerosol generating material is heated to generate an aerosol, in addition to the heating of a liquid, such as a nicotine-containing liquid or a nicotine- free liquid, which is heated by a heat source to form an aerosol or vapour. In some hybrid systems, the aerosol or vapour formed from the liquid is drawn over or through the aerosol generating material, picking up the active substance(s) and other volatilised components. In other embodiments, the aerosol or vapour formed from the liquid is not drawn over or through the aerosol generating material.

In some embodiments of the hybrid systems, the material to be heated comprises the aerosol generating material and tobacco material, such as cut tobacco. In some embodiments, one or more particles of aerosol generating material maybe incorporated into tobacco. For example, the one or more particles of aerosol generating material may be dispersed within the tobacco material, such as cut tobacco or reconstituted tobacco, to contribute to the flavour and nicotine provided by the tobacco. In other embodiments, the aerosol generating material of the hybrid system consists of the particles of aerosol generating material.

Figure 4 shows a cross-sectional view of an example of a hybrid product for heating an aerosol generating material and a liquid. The apparatus 21 has a housing 22 containing a chamber 24 which in use contains the aerosol generating material to be heated and volatilised. In this embodiment, the aerosol generating material is in the form of a monolithic aerosol generating material 23. The aerosol generating material could however be multiple particles of aerosol generating material held in the chamber or provided in a cartridge like the one illustrated in Figure 5. The housing 22 also contains a liquid reservoir 25 containing a liquid 26 to be heated to form a vapour.

The apparatus 21 further has an electronics/power chamber 27 which may, for example, contain electrical control circuitry and/or a power source (not shown). The electrical control circuitry may include a controller, such as a microprocessor arrangement, configured and arranged to control the heating of the aerosol generating material and of the liquid 26 via one or more heating elements (not shown). The electrical control circuitry may allow the apparatus 21 to be puff-actuated, so as to cause heating of the aerosol generating material “on demand”. As an alternative, the apparatus 22 may have a manually operable switch for a user to initiate a puff.

The housing 22 also includes an inlet 28 through which air is drawn into the apparatus. The housing 22 also includes an outlet 29 at a mouthpiece 30 of the apparatus 21. Air is drawn into the apparatus 21 through the inlet 28, travels through the apparatus picking up the vapour created by heating the liquid 26 in the liquid reservoir 25, and active substance(s) and volatile component released by the aerosol generating material 23, and the resulting aerosol generated by the apparatus 21 leaves the apparatus 21 through the outlet 29 and is inhaled by the user.

The hybrid device 21 shown schematically in Figure 4 represents just one possible configuration of such an apparatus. The relative positions of the liquid reservoir 25 and the aerosol generating material chamber 24 can be changed, as can the path of the air flowing through the apparatus.

In one embodiment, the liquid reservoir is positioned upstream of the aerosol generating material to be volatilised. Alternatively, the liquid reservoir may be positioned downstream of the aerosol generating material to be volatilised. In a yet further arrangement, the two sources of aerosol in the apparatus may be arranged side- by-side, etc.

In some embodiments, the vapour produced by heating the liquid in the liquid reservoir flows over or through the aerosol generating material comprising or consisting of one or more aerosol generating materials. In some embodiments, the elevated temperature of the vapour causes the active substance and volatile components to be released. Alternatively or in addition, the smoke aerosol generating able material may be separately heated by a heating means.

In some embodiments, a hybrid device is provided in which the vapour created by heating a liquid heats the aerosol generating material in order to volatilise at least one component of the aerosol generating material. In some embodiments, the liquid is a nicotine-free liquid. In other embodiments, the liquid contains nicotine. Where the aerosol generating material is heated by the vapour to volatilise at least one component of the aerosol generating material, in certain embodiments the device does not include a separate means for heating the aerosol generating material.

In other embodiments, the vapour produced by heating the liquid in the liquid reservoir does not flows over or through the aerosol generating material. Rather, this vapour and the aerosol generated by heating the aerosol generating material only mix after they are both formed.

The tobacco heating products and hybrid products described herein may, in some embodiments, include aerosol generating material in the form of containers or cartridges containing the aerosol generating material. These containers or cartridges may be removable. They may replace both the chamber holding the aerosol generating material and the aerosol generating material in the apparatus described above with reference to Figures 3 and 4, and in the alternative embodiments discussed.

Referring to Figure 5, a tobacco segment cartridge 31 is shown, comprising a housing 32 defining a cavity within which are held one or more particles of aerosol generating material (not shown). The housing 32 may, for example be made from moulded plastic or the like. In order to allow air drawn through the device to pass into the cartridge 31 and over or through the one or more particles of aerosol generating material and then out of the cartridge 31, ventilation holes 33 are provided in the housing 32 of the cartridge 31. In some embodiments, the cartridge 31 may further comprise heating means that is heatable by a suitable means in order to heat the one or more particles of aerosol generating material held therein.

Example In this experiment, menthol was used in solid particulate form as the volatile component. Menthol in powder form was added to a feedstock prior to extrusion. In addition to menthol particles, the feedstock contained ground tobacco particles, sodium carbonate (Na₂C0₃), carboxymethylcellulose (CMC) and water. The pH of the feedstock used was 8.5 for each of the samples produced. The amount of menthol added was o (a control composition), 5% and 10% by weight.

During the extrusion process, the menthol particles became structurally incorporated into the extruded tobacco granule material. Homogenous mixing of the feedstock including the menthol particles resulted in the menthol particles being homogenously distributed throughout the extruded composition. Following extrusion, the extrudate was cut into granules.

The performance of the mentholated extruded granules was tested to assess the impact of the incorporation of the menthol in the composition when the granules were incorporated into a Hybrid device.

The hybrid device included the extruded granules as the aerosol generating material, as well as a proxy (non-flavoured) liquid to form the aerosol. This liquid was used to ensure that components released from the granules into the aerosol could be accurately detected.

The data that was generated using the mentholated granules is summarised in the table below.

The various embodiments described herein are presented only to assist in understanding and teaching the claimed features. These embodiments are provided as a representative sample of embodiments only, and are not exhaustive and/or exclusive.

It is to be understood that advantages, embodiments, examples, functions, features, structures, and/ or other aspects described herein are not to be considered limitations on the scope of the invention as defined by the claims or limitations on equivalents to the claims, and that other embodiments maybe utilised and modifications maybe made without departing from the scope of the claimed invention. Various embodiments of the invention may suitably comprise, consist of, or consist essentially of, appropriate combinations of the disclosed elements, components, features, parts, steps, means, etc., other than those specifically described herein. In addition, this disclosure may include other inventions not presently claimed, but which maybe claimed in future.

The delivery system described herein can be implemented as a combustible aerosol provision system, a non-combustible aerosol provision system or an aerosol-free delivery system.

Claims

Claims l. An aerosol generating material comprising at least one particle incorporating a volatile component in solid form within said composition, and at least one particle comprising an active substance, wherein the volatile component has a vapour pressure at 20°C which is greater than or equal to the vapour pressure of the active substance at 20°C, and wherein the release of the active substance from the aerosol generating material is controlled by competition with the release of the volatile component.

2. An aerosol generating material as claimed in claim l, for inclusion in an aerosol provision system.

3. An aerosol generating material as claimed in claim l or claim 2, wherein the active substance is nicotine.

4. An aerosol generating material as claimed in any one of claims l to 3, wherein the particles comprising the active substance are tobacco particles.

5. An aerosol generating material as claimed in any one of claims 1 to 4, wherein the vapour pressure of the volatile component is at least 6 Pa at 20°C.

6. An aerosol generating material as claimed in any one of claims 1 to 5, wherein the volatile component is a volatile flavour.

7. An aerosol generating material as claimed in claim 6, wherein the volatile component is selected from the group consisting of menthol, limonene, linalool, camphene and eucalyptol.

8. An aerosol generating material as claimed in any one of claims 1 to 5, wherein the volatile component does not have a distinctive or characteristic flavour.

9. An aerosol generating material as claimed in any one of claims 1 to 8, wherein the pH of the aerosol generating material is from about 4 to about 9.5.

10. An aerosol generating material as claimed in claim 9, wherein the pH of the aerosol generating material is increased by the addition of one or more bases or a basic buffer system.

11. An aerosol generating material as claimed in claim 10, wherein the one or more base is selected from the group consisting of hydroxides, carbonates and hydrogen carbonates, optionally wherein the one or more base is selected from the group consisting of: potassium hydroxide, sodium hydroxide, sodium carbonate and sodium bicarbonate.

12. An aerosol generating material as claimed in any one of claims 1 to 11, wherein the particles comprising an active substance have an average diameter no greater than 3 mm, no greater than 1 mm, no greater than 0.5 mm, or no greater than 0.3 mm.

13. An aerosol generating material as claimed in any one of claims 1 to 12, wherein the particles incorporating a volatile component are particles that consist of the volatile component.

14. An aerosol generating material as claimed in any one of claims 1 to 13, wherein the particles incorporating a volatile component have an average diameter no greater than 3 mm, no greater than 1 mm, no greater than 0.5 mm, or no greater than 0.3 mm.

15. An aerosol generating material as claimed in any one of claims 1 to 14, further comprising one or more aerosol forming agent.

16. An aerosol generating material as claimed in claim 15, wherein the aerosol forming agent is selected from the group consisting of glycerol, propylene glycol and glyceryl triacetate.

17. An aerosol generating material as claimed in any one of claims 1 to 16, further comprising one or more binder.

18. An aerosol generating material as claimed in claim 17, wherein the one or more binder is selected from the group consisting of: thermoreversible gelling agents, such as gelatin; starches; polysaccharides; pectins; celluloses; cellulose derivatives, such as carboxymethylcellulose; and alginates.

19. An aerosol generating material as claimed in any one of claims 1 to 18, wherein a precursor composition comprising the volatile component particles and the particles comprising an active substance is granulated or spheronised to form the agglomerated structure.

20. An aerosol generating material as claimed in any one of claims 1 to 19, wherein a precursor composition comprising the volatile component particles and the particles comprising an active substance is extruded to form the agglomerated structure.

21. An aerosol generating material as claimed in any one of claims 1 to 20, in the form of granules.

22. An aerosol provision system comprising an aerosol generating material as claimed in any one of claims 1 to 21.

23. A system as claimed in claim 2, wherein the system is an aerosol generating material heating system comprising an aerosol generating material which is to be heated to volatilise constituents, and optionally including a filter or filter element.

24. A system as claimed in claim 22, wherein the system is a hybrid system comprising an aerosol generating material which is to be heated to volatilise constituents, and a liquid which is to be heated to form a vapour, and optionally including a filter or filter element.

25. A system as claimed in claim 22, wherein the aerosol generating material is heated by the vapour.

26. A system as claimed in claim 25, wherein the liquid is a nicotine-free liquid.

27. A system as claimed in claim 25 or claim 26, wherein the device includes a means for heating the liquid to form a vapour, but does not include a separate means for heating the aerosol generating material.

28. A method for preparing an aerosol generating material comprising a volatile component for use in an aerosol provision system, the method comprising incorporating the volatile component into the composition in solid form, wherein the volatile component has a vapour pressure at 20°C which is greater than or equal to the vapour pressure of the active substance at 20°C.

29. A method as claimed in claim 28, wherein the aerosol generating material is formed from a precursor composition comprising particles comprising the volatile component and particles comprising an active substance.

30. A method as claimed in claim 29, wherein the precursor composition is granulated or spheronised to form the agglomerated structure.

31. A method as claimed in claim 29, wherein the precursor composition is extruded to form the agglomerated structure.

32. An apparatus for heating aerosol generating material to volatilise at least one component of the aerosol generating material, and a nicotine-free liquid which is to be heated to form a vapour, wherein the aerosol generating material comprises an aerosol generating material as claimed in any one of claims 1 to 21, and wherein the aerosol generating material is heated by the vapour.

33. An apparatus as claimed in claim 32, including a means for heating the liquid to form a vapour, but not including a separate means for heating the aerosol generating material.

34· An apparatus as claimed in claim 32 or claim 22, wherein the pH is increased by the addition of one or more bases or a basic buffer system.

35. A particle incorporating a volatile component in solid form, wherein the volatile component has a vapour pressure at 20°C which is greater than or equal to the vapour pressure of the active substance at 20°C, for use in controlling the release of nicotine in an aerosol generating material.